Method for managing registration and session in wireless communication system and apparatus for performing the same

ABSTRACT

A communication technique that combines a 5G communication system for supporting a data rate that is higher than that of a beyond 4G system with IoT technology, and a system thereof are provided. The technique may be applied to intelligent services on the basis of 5G communication technology and IoT related technology, such as smart home, smart building, smart city, smart car or connected car, health care, digital education, retail, etc. A method of performing access deregistration by a user equipment (UE) and an apparatus therefor are provided. The method includes, when the UE is registered on both 3rd generation partnership project (3GPP) access and non-3GPP access, transmitting, to an access and mobility management function (AMF), a deregistration request message to deregister the non-3GPP access over the 3GPP access, and receiving, from the AMF, a deregistration accept message corresponding to the deregistration request message over the 3GPP access.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 15/923,383, filed on Mar. 16, 2018, which has issued as U.S. Pat.No. 10,932,218 on Feb. 23, 2021 and is based on and claims priorityunder 35 U.S.C § 119(a) of a Korean patent application number10-2017-0033343, filed on Mar. 16, 2017, in the Korean IntellectualProperty Office, the disclosure of which is incorporated by referenceherein in its entirety.

TECHNICAL FIELD

The disclosure relates to a method for processing a registration requestmessage for registering on a 5G network by a terminal in accordance withan access management function (AMF) issuing a temporary user identity(ID) when registering on the 5G network using the temporary user ID.

Further, the disclosure relates to a method for processing a PDU sessionestablishment request by a terminal in consideration of whether tosupport a PDU session type of a session management function (SMF) in aprocess of making a PDU session for servicing traffics in a mobilecommunication system.

Further, the disclosure relates to a method for effectively managingregistration and session management by a terminal when a coverage lossfor a non-3GPP access occurs in a situation where the terminal accessesa 5G network through a 3GPP access and a non-3GPP access.

BACKGROUND

In order to meet the demand for wireless data traffic that is on anincreasing trend after commercialization of 4G communication systems,efforts have been made to develop improved 5G or pre-5G communicationsystem. For this reason, the 5G or pre-5G communication system is alsocalled a beyond 4G network communication system or a post LTE system.

In order to achieve high data rate, implementation of a 5G communicationsystem in an ultrahigh frequency (mmWave) band (e.g., like 60 GHz band)has been considered. In order to mitigate a path loss of radio waves andto increase a transfer distance of the radio waves in the ultrahighfrequency band, technologies of beamforming, massive MIMO, fulldimension MIMO (FD-MIMO), array antennas, analog beamforming, andlarge-scale antennas for the 5G communication system have beendiscussed.

Further, for system network improvement in the 5G communication system,technology developments have been made for an evolved small cell,advanced small cell, cloud radio access network (cloud RAN), ultra-densenetwork, device to device communication (D2D), wireless backhaul, movingnetwork, cooperative communication, coordinated multi-points (CoMP), andreception interference cancellation.

In addition, in the 5G system, hybrid FSK and QAM modulation (FQAM) andsliding window superposition coding (SWSC), which correspond to advancedcoding modulation (ACM) systems, and filter bank multicarrier (FBMC),non-orthogonal multiple access (NOMA), and sparse code multiple access(SCMA), which correspond to advanced connection technologies, have beendeveloped.

On the other hand, the Internet, which is a human centered connectivitynetwork where humans generate and consume information, is now evolvingto the Internet of things (IoT) where distributed entities, such asthings, exchange and process information. The Internet of everything(IoE), which is a combination of the IoT technology and big dataprocessing technology through connection with a cloud server, hasemerged. As technology elements, such as sensing technology,wired/wireless communication and network infrastructure, serviceinterface technology, and security technology, have been demanded forIoT implementation, a sensor network for machine-to-machine connection,machine-to-machine (M2M) communication, machine type communication(MTC), and so forth have been recently researched. Such an IoTenvironment may provide intelligent Internet technology (IT) servicesthat create a new value to human life by collecting and analyzing datagenerated among connected things. The IoT may be applied to a variety offields including smart home, smart building, smart city, smart car orconnected cars, smart grid, health care, smart appliances and advancedmedical services through convergence and combination between theexisting information technology (IT) and various industries.

Accordingly, various attempts have been made to apply the 5Gcommunication system to IoT networks. For example, technologies ofsensor network, machine to machine (M2M) communication, and MTC havebeen implemented by techniques for beam-forming, MIMO, and arrayantennas, which correspond to the 5G communication technology. As thebig data processing technology as described above, application of acloud radio access network (cloud RAN) would be an example ofconvergence between the 5G technology and the IoT technology.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providean apparatus and method, for a terminal that can effectively proceedwith a registration process using a UE context for the previous accessthrough a temporary user ID and a context of a terminal currentlyaccessing through another access when registering on a 5G network usingthe temporary user ID. However, it is necessary that the operation of anAMF differs depending on whether the context indicated by the temporaryuser ID is the UE context for the previous access or the context of theterminal currently accessing through another access, and an aspect ofthe disclosure provides a method by a terminal for processing aregistration request message for registering on the 5G network inaccordance with the state of the temporary user ID.

In accordance with another aspect of the disclosure, in a mobilecommunication system, a terminal sends to an AMF a PDU sessionestablishment request to make a PDU session for servicing traffics, andthe AMF generates the PDU session by processing the PDU sessionestablishment request message through selection of an SMF.

Another aspect of the disclosure is to provide a method for resuming anSMF selection so that the SMF supporting the PDU session type requestedby the terminal can process the PDU session establishment request if theSMF does not support the PDU session type requested by the terminal, forexample, an IP version.

Still another aspect of the disclosure is to provide a method forprocessing a PDU session being serviced through the existing non-3GPPaccess (or non-3gpp access) and processing a registration state througha non-3gpp access if a terminal secedes from a coverage for the non-3gppaccess in a situation where the terminal accesses a 5G network through a3GPP access (or 3gpp access) and the non-3gpp access. If the PDU sessionis continuously maintained or the registration situation is maintainedas it is with respect to the non-3gpp access in the 5G network,unnecessary resources are to be used, and thus it is necessary toprovide a method for effectively managing the registration and PDUsession for the non-3gpp access through the 3gpp access.

In accordance with an aspect of the disclosure, a method for processinga control signal in a wireless communication system is provided. Themethod includes receiving a first control signal transmitted from a basestation providing processing the received first control signal, andtransmitting to the base station a second control signal generated basedon the process.

According to an aspect of the disclosure, it is possible to effectivelyprocess the registration request message sent by the terminal thatperforms registration using the temporary user ID through thedisclosure.

Further, according to another aspect of the disclosure, the terminal cansuccessfully make the PDU session through selection of the SMF to suitthe PDU session type in which the terminal intends to service thetraffics to enable the traffic service to be smoothly used through thedisclosure.

Further, according to still another aspect of the disclosure, it ispossible to efficiently perform the terminal registration management andthe PDU session management through the 3gpp access in a situation wherethe terminal is unable to use the non-3gpp access, such as in asituation where the terminal secedes from the coverage of the non-3gppaccess, and thus it is possible to efficiently manage the resources inthe 5G network through the disclosure.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a diagram illustrating an example of a cellular networkstructure using a common AMF if a PLMN of a 3gpp access is the same as aPLMN of an N3IWF when a terminal performs an access through the 3gppaccess and a non-3gpp access according to an embodiment of thedisclosure;

FIG. 2 is a diagram illustrating a process of routing a registrationrequest message based on a temporary user ID when a terminal uses thetemporary user ID as routing information being transferred to RAN orN3IWF in a registration process according to an embodiment of thedisclosure;

FIG. 3 is a diagram illustrating a process in which an AMF havingreceived a registration request message including a temporary user IDprocesses a registration request message in a terminal registrationprocess according to an embodiment of the disclosure;

FIG. 4 is a diagram illustrating a process in which an AMF havingreceived a registration request message including a temporary user IDprocesses a registration request message in a terminal registrationprocess according to an embodiment of the disclosure;

FIG. 5 is a diagram illustrating an example of a 5G network structurefor a terminal according to an embodiment of the disclosure;

FIG. 6 is a diagram that exemplifies a procedure of selecting an SMF inconsideration of a PDU session type and forwarding a PDU sessionestablishment request to the selected SMF when a terminal sends the PDUsession establishment request to a 5G network according to an embodimentof the disclosure;

FIG. 7 is a diagram that exemplifies a process in which an AMF discoversa suitable SMF through an NRF according to an embodiment of thedisclosure;

FIG. 8 is a diagram that exemplifies a process in which an AMF discoversa suitable SMF through an NRF according to an embodiment of thedisclosure;

FIG. 9 is a diagram illustrating an example of a structure in which aterminal accesses a 5G network through a 3gpp access and a non-3gppaccess according to an embodiment of the disclosure;

FIG. 10 is a diagram illustrating a process in which a terminal locallyreleases a PDU session of a non-3gpp access or locally deregisters anon-3gpp if the terminal accessing a 5G network through a 3gpp accessand the non-3gpp access is unable to use the non-3gpp access accordingto an embodiment of the disclosure;

FIG. 11 is a diagram illustrating a process in which a terminal releasesa PDU session of a non-3gpp access or deregisters a non-3gpp through a3gpp access if the terminal accessing a 5G network through the 3gppaccess and the non-3gpp access is unable to use the non-3gpp accessaccording to an embodiment of the disclosure;

FIG. 12 is a diagram illustrating a process in which a terminaltransfers a PDU session of a non-3gpp access to a 3gpp access throughthe 3gpp access if the terminal accessing a 5G network through the 3gppaccess and the non-3gpp access is unable to use the non-3gpp accessaccording to an embodiment of the disclosure;

FIG. 13 is a diagram illustrating a process of releasing a PDU sessionof a non-3gpp access or deregistering a non-3gpp if an AMF recognizesthrough an N3IWF that a terminal accessing a 5G network through a 3gppaccess and the non-3gpp access is unable to use the non-3gpp accessaccording to an embodiment of the disclosure;

FIG. 14 is a diagram illustrating a process of releasing a PDU sessionof a non-3gpp access or deregistering a non-3gpp through a 3gpp accessif an AMF recognizes through an N3IWF that a terminal accessing a 5Gnetwork through the 3gpp access and the non-3gpp access is unable to usethe non-3gpp access according to an embodiment of the disclosure;

FIG. 15 is a diagram illustrating a process of switching a PDU sessionof a non-3gpp access to a 3gpp access through the 3gpp access if an AMFrecognizes through an N3IWF that a terminal accessing a 5G networkthrough the 3gpp access and the non-3gpp access is unable to use thenon-3gpp access according to an embodiment of the disclosure;

FIG. 16 is a diagram illustrating a process of performing registrationmanagement and connection management if a terminal accessing a 5Gnetwork through a 3gpp access and a non-3gpp access recognizes that itis unable to use the non-3gpp access according to an embodiment of thedisclosure;

FIG. 17 is a diagram illustrating a process of performing registrationmanagement and connection management if an AMF recognizes through anN3IWF that a terminal accessing a 5G network through a 3gpp access and anon-3gpp access is unable to use the non-3gpp access according to anembodiment of the disclosure;

FIG. 18 is a diagram illustrating a structure of a network entityaccording to an embodiment of the disclosure; and

FIG. 19 is a diagram illustrating a structure of a terminal according toan embodiment of the disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness. In describingthe disclosure, related well-known functions or configurationsincorporated herein are not described in detail in the case where it isdetermined that they obscure the subject matter of the disclosure inunnecessary detail.

Further, terms to be described later are terms defined in considerationof their functions in the disclosure, but may differ depending onintentions of a user and an operator or customs. Accordingly, theyshould be defined based on the contents of the whole description of thedisclosure.

The aspects and features of the disclosure and methods for achieving theaspects and features will be apparent by referring to the embodiments tobe described in detail with reference to the accompanying drawings.However, the disclosure is not limited to the embodiments disclosedhereinafter, but can be implemented in diverse forms. The mattersdefined in the description, such as the detailed construction andelements, are nothing but specific details provided to assist those ofordinary skill in the art in a comprehensive understanding of thedisclosure, and the disclosure is only defined within the scope of theappended claims. In the entire description of the disclosure, the samedrawing reference numerals are used for the same elements across variousfigures.

First Embodiment

Hereinafter, the operation principle of the disclosure will be describedin detail with reference to the accompanying drawings. In describing thedisclosure hereinafter, detailed explanation of the related well-knownfunctions or configurations incorporated herein will be omitted if it isdetermined that they obscure the subject matter of the disclosure inunnecessary detail. Further, terms to be described later are termsdefined in consideration of their functions in the disclosure, but maydiffer depending on intentions of a user and an operator or customs.Accordingly, they should be defined based on the contents of the wholedescription of the disclosure.

Hereinafter, terms for identifying a connection node, terms for callingnetwork entities, terms for calling an interface between networkentities, and terms for calling various pieces of identificationinformation, as used in the following description, are exemplified forconvenience in explanation. Accordingly, the disclosure is not limitedto the terms to be described later, but other terms for calling subjectshaving equal technical meanings may be used.

Hereinafter, for convenience in explanation, terms and titles that aredefined in the 5G system standards are used in the disclosure. However,the disclosure is not limited by the terms and titles, but can beequally applied to systems following other standards. Further, anon-3gpp access includes an access through WiFi, and may be equallyapplied with respect to other accesses excluding the access through 5G.

Hereinafter, a temporary UE ID and a temporary user ID, used in thedescription and drawings, may be the same parameter having a valueallocated to a terminal if the terminal has successfully registered on a5G network. In an LTE system, the temporary UE ID and the temporary userID are temporary IDs having the same function as the function of a GUTI,and may be mixedly used for convenience.

FIG. 1 is a diagram illustrating an example of a cellular networkstructure using a common AMF if a PLMN of a 3gpp access is the same as aPLMN of an N3IWF when a terminal performs an access through the 3gppaccess and a non-3gpp access according to an embodiment of thedisclosure.

Referring to FIG. 1 , when accessing the network through 3gpp access,the terminal (1-01) communicates through the RAN (1-02), common AMF(1-03), SMF (1-04, 1-05) and, when accessing the network throughnon-3gpp access (1-06), the terminal 1-01 communicates with the N3IWF(1-07), common AMF (1-03), SMF (1-04, 1-05).

Referring to FIG. 1 , if a terminal accesses a 5G core network through a3gpp access, that is, a 5G RAN, and simultaneously accesses the 5G corenetwork through a non-3gpp access, an N3IWF selected by the terminal forthis may be in the same PLMN as the PLMN of the non-3gpp access, and inthis case, the same common AMF may be selected.

If the terminal performs registration in a state where a valid temporaryuser ID exists, it transmits a registration request message includingthe temporary user ID. In this case, it is necessary for the AMF thathas received the registration request message to discriminate whetherthe temporary user ID is a temporary user ID that the terminal hasreceived from the already registered AMF through another access type(e.g., 3gpp access) or a temporary user ID received from the AMF in theprevious registration process. That is, if the temporary user ID hasbeen received from the already registered AMF through another accesstype, the newly selected AMF performs registration through relocation tothe AMF to which the temporary user ID was allocated, whereas if thetemporary user ID has been received from the AMF in the previousregistration process, the newly selected AMF continuously performs theremaining registration process by bring a UE context from the AMF towhich the temporary user ID was allocated.

Here, the N3IWF is 5G core network equipment defined for smoothinterlocking between the non-3gpp access and the 5G core network, and isan entity that serves to forward a NAS message or datatransmitted/received through the non-3gpp access. The N3IWF is alsocalled ngPDG.

FIG. 2 is a diagram illustrating a process of routing a registrationrequest message based on a temporary user ID when a terminal uses thetemporary user ID as routing information being transferred to RAN orN3IWF in a registration process according to an embodiment of thedisclosure.

When a terminal 2-01 performs registration (2-11) in a situation whereit has a previously allocated temporary user ID, it checks whether ithas already been registered through another access type and whether thetemperature user ID is a temporary user ID that is managed by an AMFcurrently serving the terminal (2-12). For example, the terminal may bein a situation where it has already registered on a 5G network through a3gpp access and uses the temporary user ID issued by the registered AMF,or may be in a situation where it has already registered on the 5Gnetwork through a non-3gpp access and uses the temporary user ID issuedby the registered AMF.

In this case, when sending the registration request message through anAS layer, the terminal may include the temporary user ID in theregistration request message as routing information. In this case, if itis determined that the temporary user ID is a temporary user IDallocated by the AMF serving the terminal through another access type,the terminal adds an indication for notifying that the temporary user IDhas been allocated to the terminal during registration through anotheraccess. Accordingly, the RAN or N3IWF 2-02 that has received the routinginformation routes the registration request message to the AMF allocatedwith the temporary user ID (2-16).

FIG. 3 is a diagram illustrating a process in which an AMF havingreceived a registration request message including a temporary user IDprocesses a registration request message in a terminal registrationprocess according to an embodiment of the disclosure.

When a terminal 3-01 performs registration (3-11) in a situation whereit has a previously allocated temporary user ID, it checks whether ithas already been registered through another access type and whether thetemperature user ID is a temporary user ID that is managed by an AMFcurrently serving the terminal (3-12). For example, the terminal may bein a situation where it has already registered on a 5G network through a3gpp access and uses the temporary user ID issued by the registered AMF,or may be in a situation where it has already registered on the 5Gnetwork through a non-3gpp access and uses the temporary user ID issuedby the registered AMF.

In this case, the terminal may include the temporary user ID in theregistration request message so that it can select a suitable AMF whensending the registration request message. In this case, if it isdetermined that the temporary user ID is a temporary user ID allocatedby the AMF serving the terminal through another access type, theterminal adds an indication for notifying that the temporary user ID hasbeen allocated to the terminal during registration through anotheraccess to the registration request message. The AMF having received theregistration request message determines a scheme for processing theregistration request as in the process (3-15). For example, in order tobring a UE context from the AMF designated by the temporary user ID in acase where an indication for notifying that the temporary user ID hasbeen allocated to the terminal during registration through anotheraccess is not included, or an indication for notifying that thetemporary user ID is a temporary user ID received during the previousregistration is included, the AMF sends an information request messageto the AMF designated by the temporary user ID (3-16). In contrast, incase of receiving the registration request message including theindication for notifying that the temporary user ID has been allocatedto the terminal during the registration through another access, the AMFrecognizes that the attached temporary user ID corresponds to the AMFcurrently servicing the terminal, and reroutes the registration requestmessage to the AMF designated by the temporary user ID. That is, as in aprocess (3-17 a), the AMF (e.g., AMF1 3-03) may directly send theregistration request message that is carried on a reroute NAS message tothe AMF (e.g., AMF2 3-04) designated by the temporary user ID, or as ina process (3-17 b), it may reroute the registration request message thatis carried on the reroute NAS message to the RAN or N3IWF 3-02. In thiscase, the reroute NAS message may include information on the AMFdesignated by the temporary user ID.

FIG. 4 is a diagram illustrating a process in which an AMF havingreceived a registration request message including a temporary user IDprocesses a registration request message in a terminal registrationprocess according to an embodiment of the disclosure.

When a terminal 4-01 performs registration (4-11) in a situation whereit has a previously allocated temporary user ID, it sends theregistration request message including the temporary UE ID (4-13).

If the AMF having received the registration request message does nothave a UE context for the temporary UE ID, it sends an informationrequest message to the AMF designated by the temporary UE ID in order tobring a UE context from the AMF designated by the temporary user ID(4-14). The information request message may include parts or all ofaddress information of RAN/N3IWF 4-02 having sent the registrationrequest message, access type related access information, and N2 tunnelinformation with the AMF.

The AMF (e.g., AMF2 4-04) having received the information requestmessage determines whether to send the UE context for the temporary UEID to the AMF that has requested the same or to reroute the registrationrequest message to the AMF itself (4-15 and 4-16). That is, if it isdetermined that the AMF allocates and uses the temporary UE ID duringthe registration through another access type (e.g., 3gpp access), itreroutes the registration request message transferred through thenon-3gpp access to itself in order to use the same AMF regardless of theaccess type. Here, a method in which the AMF determines that itallocates and uses the temporary UE ID during the registration throughanother access may be known from information on the access type includedin the registration request message, or if the registration typeincluded in the registration request message is “initial registration”,the registration through another access type can be known. Further, theregistration through another access type may be known through addressinformation of the RAN/N3IWF 4 d-02 or access type related accessinformation included in the information request, or the registrationthrough another access type may be known through synthesis anddetermination of the parts or all of the above-described schemes.

In contrast, in case of changing the AMF through the registration, suchas in case of changing the AMF in accordance with movement of theterminal or in case of changing the AMF having performed theregistration through the existing non-3gpp access to the AMF forregistration through the 3gpp access, the AMF sends the UE context forthe temporary UE ID to the AMF that has requested the same (4-16).

Accordingly, in case of changing the AMF when the information responsemessage is sent in the process (4-17), the AMF transfers the UE contextto a new AMF having requested the same. In contrast, in case ofrerouting the AMF to itself, the AMF may include a relocation request inthe information response message to be sent. The new AMF having receivedthe relocation request recognizes that the attached temporary user IDcorresponds to the AMF currently servicing the terminal, and reroutesthe registration request message to the AMF designated by the temporaryuser ID. That is, as in a process (4-18 a), the AMF may directly sendthe registration request message that is carried on a reroute NASmessage to the AMF designated by the temporary user ID, or as in aprocess (4-18 b), it may reroute the registration request message thatis carried on the reroute NAS message to the RAN or N3IWF 4-02 that hassent the registration request message. In this case, the reroute NASmessage may include information on the AMF designated by the temporaryuser ID.

As another embodiment for rerouting the AMF to itself, the AMF includesrelocation completion in an information response message, and the AMFitself serves as a serving AMF. In this case, using the addressinformation of the RAN/N3IWF 4-02 or N2 tunnel information with the AMFincluded in the information request message, the AMF sends an N2 messageto the RAN/N3IWF 4-02 to correct the N2 tunnel information between theAMF and the RAN/N3IWF.

In the embodiments of the disclosure as described above, constituentelements included in the disclosure are expressed in a singular form orin a plural form. However, such a singular or plural expression isselected to suit a situation presented for convenience in explanation,and thus the disclosure is not limited to such singular or pluralconstituent elements. Even plural constituent elements may be expressedin a singular form, and even a single constituent element may beexpressed in a plural form.

On the other hand, although detailed embodiments of the disclosure havebeen described in the specification and drawings, it will be apparentthat various modifications are possible within the scope of thedisclosure. Accordingly, the scope of the disclosure should not belimited to the embodiments as described above, but should be defined bythe appended claims below and those equivalent to the scope of theclaims.

Second Embodiment

Hereinafter, the operation principle of the disclosure will be describedin detail with reference to the accompanying drawings. In describing thedisclosure hereinafter, detailed explanation of the related well-knownfunctions or configurations incorporated herein will be omitted if it isdetermined that they obscure the subject matter of the disclosure inunnecessary detail. Further, terms to be described later are termsdefined in consideration of their functions in the disclosure, but maydiffer depending on intentions of a user and an operator or customs.Accordingly, they should be defined based on the contents of the wholedescription of the disclosure.

Hereinafter, terms for identifying a connection node, terms for callingnetwork entities, terms for calling an interface between networkentities, and terms for calling various pieces of identificationinformation, as used in the following description, are exemplified forconvenience in explanation. Accordingly, the disclosure is not limitedto the terms to be described later, but other terms for calling subjectshaving equal technical meanings may be used.

FIG. 5 is a diagram illustrating an example of a 5G network structurefor a terminal according to an embodiment of the disclosure.

Referring to FIG. 5 , a terminal performs registration on a 5G corenetwork by accessing an AMF through a (R)AN. If the terminal sends a PDUsession establishment request to the AMF through the (R)AN to receive atraffic service, the AMF selects a suitable SMF. In this process, inorder to discover the SMF, the AMF requests an NRF to discover the SMF,and in response to this, the NRF transfers address information of thediscovered SMF to the AMF to make the AMF select a suitable SMF.

If the PDU session establishment request is transferred to the selectedSMF, a PDU session production procedure is performed to allocate anaddress to the terminal in accordance with the PDU session establishmentrequest, to select a UPF that is a G/W for sending/receiving trafficswith outside, and to allocate resource3s.

FIG. 6 is a diagram that exemplifies a procedure of selecting an SMF inconsideration of a PDU session type and forwarding a PDU sessionestablishment request to the selected SMF when a terminal sends the PDUsession establishment request to a 5G network according to an embodimentof the disclosure.

The terminal 6-01 generates and sends a PDU session establishmentrequest to an AMF (6-10). The PDU session establishment request messageincludes parts or all of DNN or S-NSSAI information requested by theterminal, a PDU session type, and a PDU session ID allocated by theterminal. The PDU session type may be IPv4, IPv6, Ethernet type, or anunstructured PDU session type.

The AMF (e.g., AMF 6-02) having received the PDU session establishmentrequest from UE 6-01, may send an SMF discovery to an NRF 6-03 inconsideration of the DNN information or S-NSSAI information (6-11), andin response to this, it receives a discovery response including addressinformation of discovered SMFs (6-12). Based on the received informationof the SMFs, the AMF performs SMF selection (6-13).

In particular, as an embodiment for AMF and NRF operation schemes in theabove-described processes (6-11, 6-12, and 6-13), if the AMF can receivethe PDU session establishment request and analyze the PDU session typein addition to the DNN and S-NSSAI information requested by theterminal, the AMF may request an SMF discovery through inclusion of thePDU session type in addition to the DNN and S-NSSAI information duringrequesting the SMF discovery at operation 6-11. In response to this, theNRF sends the discovery response including address information or IDinformation of the SMF satisfying the PDU session type and DNN andS-NSSAI information requested at operation 6-11 (6-12), and the AMFselects a suitable one of the received SMFs (6-13).

As another embodiment for AMF and NRF operation schemes in theabove-described processes (6-11, 6-12, and 6-13), if the AMF can receivethe PDU session establishment request and analyze the PDU session typein addition to the DNN and S-NSSAI information requested by theterminal, the AMF may request an SMF discovery through inclusion of theDNN and S-NSSAI information during requesting the SMF discovery atoperation 6-11. In response to this, the NRF sends the discoveryresponse including address information or ID information of the SMFsatisfying the DNN and S-NSSAI information requested at operation 6-11(6-12), load information of the SMF, and information on the PDU sessiontype supported by the SMF (6-12), and the AMF selects a suitable one ofthe received SMFs supporting the PDU session type requested by theterminal (6-13).

As still another embodiment for AMF and NRF operation schemes in theabove-described processes (6-11, 6-12, and 6-13), although the AMF canreceive the PDU session establishment request and analyze the DNN andS-NSSAI information requested by the terminal, but it cannot analyze thePDU session type requested by the terminal, the AMF may request an SMFdiscovery through inclusion of the DNN and S-NSSAI information duringrequesting the SMF discovery at operation 6-11. In response to this, theNRF sends the discovery response including address information or IDinformation of the SMF satisfying the DNN and S-NSSAI informationrequested at operation 6-11, load information of the SMF, andinformation on the PDU session type supported by the SMF (6-12), and theAMF selects a suitable one of the received SMFs. However, in this case,since the AMF does not know the information on the PDU session typerequested by the terminal, it selects the SMF without considering thePDU session type (6-13). However, the AMF may store SMF information tobe used for choosing the SMF later and information on the PDU sessiontypes.

On the other hand, after the SMF is selected through the process (6-13),the AMF transfers the PDU session establishment request message includedin an SM request message to the selected SMF (6-14).

The SMF having received the request message checks whether it supportsthe PDU session establishment request requested by the terminal. Inparticular, the SMF (e.g., SMF1 6-04) checks whether it supports the PDUsession type requested by the terminal (6-15). If the SMF supports thePDU session type, it continuously performs the remaining PDU sessionestablishment process, such as authentication/authorization of the PDUsession establishment request, UPF allocation, and resource reservation,without reselecting the SMF at operation 6-16 (6-22).

In contrast, if the selected SMF does not support the PDU session typerequested by the terminal, it reselects the SMF in accordance with theprocess (6-16). That is, as sending an ACK to the SM request, the SMFmay include a cause so as to indicate that the SM request has not beenwell processed and to redirect the PDU session establishment requestmessage through selection of another SMF supporting the PDU session typerequested by the terminal, and may also include information on the PDUsession type requested by the terminal together with the cause.

If the ACK to the SM request is received, the SMF may select a suitableSMF supporting the PDU session type requested by the terminal using SMFaddress information or ID information acquired at operations 6-11 and6-12 and information on the PDU session types supported by the SMF, ormay grasp information on the SMF again using the NRF. That is, an SMFdiscovery request message is sent to the NRF (6-18), and in response tothis, SMF address information or ID information and information on thePDU session types supported by the SMF are acquired (6-19). Based on theacquired information, a suitable SMF supporting the PDU session typerequested by the terminal is selected (6-20).

In particular, as an embodiment for AMF and NRF operation schemes in theabove-described processes (6-18, 6-19, and 6-20), the AMF may requestthe SMF discovery including the PDU session type in addition to the DNNand S-NSSAI information during requesting of the SMF discovery atoperation 6-11 in consideration of the PDU session type requested by theterminal and acquired through operation 6-17. In response to this, theNRF sends a discovery response including address information or IDinformation of the SMF or load information of the SMF satisfying the PDUsession type requested at operation 6-18 and DNN and S-NSSAI information(6-19), and the AMF selects a suitable one of the received SMFs (6-20).

As another embodiment for AMF and NRF operation schemes in theabove-described processes (6-18, 6-19, and 6-20), the AMF may requestthe SMF discovery including the DNN and S-NSSAI information duringrequesting of the SMF discovery at operation 6-11. In response to this,the NRF sends a discovery response including address information or IDinformation of the SMF or load information of the SMF satisfying the DNNand S-NSSAI information requested at operation 6-18, and information onthe PDU session type supported by the SMF (6-19), and the AMF selects asuitable one of the received SMFs supporting the PDU session typerequested by the terminal (6-20).

On the other hand, after the SMF is selected through the process (6-20),the AMF transfers the PDU session establishment request message includedin the SM request message to the selected SMF (6-21). The SMF havingreceived the PDU session establishment request continuously perform theremaining PDU session establishment process, such as such asauthentication/authorization of the PDU session establishment request,UPF allocation, and resource reservation (6-22).

FIG. 7 is a diagram that exemplifies a process in which an AMF discoversa suitable SMF through an NRF according to an embodiment of thedisclosure.

FIG. 7 is a diagram that exemplifies a process in which an AMF discoversa suitable SMF through an NRF at operations 6-11 and 6-12 or operations6-18 and 6-19 of FIG. 6 according to the disclosure.

The AMF may receive the PDU session establishment request, and in orderto select the SMF, the AMF may request the SMF discovery including DNNand S-NSSAI information and UE location information during requesting ofthe SMF discovery at operation 7-04. In response to this, the NRF sendsthe discovery response including address information or ID informationof the SMF satisfying information requested at operation 7-05, loadinformation of the SMF, and PDU session type information supported bythe SMF (7-05).

If the PDU session type information requested by the terminal isacquired, the AMF selects the SMF supporting the PDU session typerequested by the terminal among the discovered SMFs.

FIG. 8 is a diagram that exemplifies a process in which an AMF discoversa suitable SMF through an NRF according to an embodiment of thedisclosure.

FIG. 8 is a diagram that exemplifies a process in which an AMF 8-01discovers a suitable SMF through an NRF 8-02 at operations 6-11 and 6-12or operations 6-18 and 6-19 of FIG. 6 according to the disclosure.

The AMF 8-01 may receive the PDU session establishment request, and inorder to select the SMF, the AMF 8-01 may request the SMF discoveryincluding DNN and S-NSSAI information, UE location information, and PDUsession type information requested by the terminal during requesting ofthe SMF discovery at operation 8-04. In response to this, the NRF 8-02sends the discovery response including address information or IDinformation of the SMF satisfying information requested at operation8-05, and load information of the SMF (8-05).

The AMF selects the SMF among the discovered SMFs.

In the embodiments of the disclosure as described above, constituentelements included in the disclosure are expressed in a singular form orin a plural form. However, such a singular or plural expression isselected to suit a situation presented for convenience in explanation,and thus the disclosure is not limited to such singular or pluralconstituent elements. Even plural constituent elements may be expressedin a singular form, and even a single constituent element may beexpressed in a plural form.

On the other hand, although detailed embodiments of the disclosure havebeen described in the specification and drawings, it will be apparentthat various modifications are possible within the scope of thedisclosure. Accordingly, the scope of the disclosure should not belimited to the embodiments as described above, but should be defined bythe appended claims below and those equivalent to the scope of theclaims.

Third Embodiment

Hereinafter, the operation principle of the disclosure will be describedin detail with reference to the accompanying drawings. In describing thedisclosure hereinafter, detailed explanation of the related well-knownfunctions or configurations incorporated herein will be omitted if it isdetermined that they obscure the subject matter of the disclosure inunnecessary detail. Further, terms to be described later are termsdefined in consideration of their functions in the disclosure, but maydiffer depending on intentions of a user and an operator or customs.Accordingly, they should be defined based on the contents of the wholedescription of the disclosure.

Hereinafter, terms for identifying a connection node, terms for callingnetwork entities, terms for calling an interface between networkentities, and terms for calling various pieces of identificationinformation, as used in the following description, are exemplified forconvenience in explanation. Accordingly, the disclosure is not limitedto the terms to be described later, but other terms for calling subjectshaving equal technical meanings may be used.

Hereinafter, for convenience in explanation, terms and titles that aredefined in the 5G system standards are used in the disclosure. However,the disclosure is not limited by the terms and titles, but can beequally applied to systems following other standards. Further, anon-3gpp access includes an access through WiFi, and may be equallyapplied with respect to other accesses excluding the access through 5G.

FIG. 9 illustrates an example of a structure in which a terminalaccesses a 5G network through a non-3gpp access according to anembodiment of the disclosure. In particular, FIG. 9 also illustrates astructure in which the terminal uses a common AMF by accessing through a3gpp access and the non-3gpp access.

Referring to FIG. 9 , when the terminal 9-01 accesses the networkthrough 3gpp access, the terminal 9-01 communicates through the RAN9-02, AMF 9-03, SMF 9-04, 9-06, UPF 9-05 and 9-09. When the terminal9-01 accesses the network through the non-3gpp access 9-07, the terminal9-01 communicates through the N3IWF 9-08, the AMF 9-03, the SMF 9-06),and the UPF (9-09).

Referring to FIG. 9 , if a terminal accesses a 5G core network through a3gpp access, that is, a 5G RAN, and simultaneously accesses the 5G corenetwork through a non-3gpp access, a common AMF is selected. Theterminal accesses a 5G core network through a 3gpp access and a non-3gppaccess, and the AMF manages registration separately with respect to the3gpp and non-3gpp.

Here, an N3IWF is 5G core network equipment defined for smoothinterlocking between the non-3gpp access and the 5G core network, and isan entity that serves to forward a NAS message or datatransmitted/received through the non-3gpp access. The N3IWF is alsocalled ngPDG. The SMF is an entity serving to manage the session and toallocate an IP address to the terminal, and a UPF serves to forward userdata under the control of the SMF.

According to an embodiment of the disclosure, in a case where the AMFmanages registration through the non-3gpp access, the method formanaging the registration may differ depending on whether thecorresponding terminal has the registration through the 3gpp access.

For example, if the terminal becomes unable to use the service of the 5Gnetwork through the non-3gpp access, such as if the terminal secedesfrom the coverage of the non-3gpp access or if a non-3gpp access moduleis switched off, in a state where the corresponding terminal has theregistration through the 3gpp access and the registration through thenon-3gpp access, the terminal and the 5G core network can efficientlyperform resource management by processing a PDU session being servicedby the non-3gpp access through the 3gpp access or by performingderegistration for the non-3gpp access.

FIG. 10 illustrates a process in which a terminal locally releases a PDUsession of a non-3gpp access or locally deregisters a non-3gpp if theterminal accessing a 5G network through a 3gpp access and the non-3gppaccess is unable to use the non-3gpp access according to an embodimentof the disclosure.

A terminal 10-01 that has successfully registered on a 5G networkthrough a 3gpp access and a non-3gpp access uses a PDU session generatedthrough the non-3gpp access (10-11).

In this case, if the terminal becomes unable to perform the non-3gppaccess, such as if the terminal secedes from a coverage for the non-3gppaccess or if a non-3gpp access module is turned off, the terminaloperates a timer and waits for until the non-3gpp access can be usedagain for a predetermined time (10-12).

If the use of the non-3gpp access is still impossible, such as if theterminal returns to the coverage for the non-3gpp access or the non-3gppaccess module is turned on again, until the timer expires, the terminalmay locally release the PDU sessions being used through the non-3gppaccess or may locally perform deregistration for the non-3gpp access inaccordance with the existing configuration or a user's input (10-13).

On the other hand, since the terminal has been registered for the 3gppaccess, it sends the registration request message to the AMF through the3gpp access in order to update the registration in accordance withmobility of the terminal or periodically (10-14). In this case, theregistration request message may include an item for the PDU session forthe non-3gpp access or the deregistration situation.

For example, the terminal may include an indication for notifying thesituation in which the terminal has already released the PDU session IDused through the non-3gpp access, or an indication for notifying thatthe terminal has already performed deregistration for the non-3gppaccess.

The AMF having received the registration request message including theabove-described indication synchronizes the state for the correspondingPDU session in the 5G core network and the registration state for thenon-3gpp access with the terminal in accordance with the above-describedindication (10-15).

For example, if the indication indicates that the terminal has alreadyreleased the PDU session ID used through the non-3gpp access, the AMFsends a PDU session release request to the SMF managing the PDU sessioncorresponding to the PDU session ID to make the SMF and the UPF releasethe PDU session corresponding to the PDU session ID, and notifies theN3IWF to release a tunnel between the N3IWF and the UPF through the AMFso as to erase the PDU sessions used through the non-3gpp access fromthe 5G network.

Further, if the indication indicates that the terminal has alreadyreleased the PDU session ID used through the non-3gpp access, the AMFreleases all PDU sessions being used through the non-3gpp access throughthe PDU session release procedure, and sets deregistration of theregistration state for the non-3gpp access.

The processing result may be included in a registration accept messageto be sent to the terminal.

That is, the terminal may include an indication for notifying that thePDU session ID, of which the release has been notified by the terminal,has been released or an indication for notifying that the 5G corenetwork has been deregistered for the non-3gpp access (10-16).

FIG. 11 illustrates a process in which a terminal releases a PDU sessionof a non-3gpp access or deregisters a non-3gpp through a 3gpp access ifthe terminal accessing a 5G network through the 3gpp access and thenon-3gpp access is unable to use the non-3gpp access according to anembodiment of the disclosure.

A terminal 11-01 that has successfully registered on a 5G networkthrough a 3gpp access and a non-3gpp access uses a PDU session generatedthrough the non-3gpp access (11-11).

In this case, if the terminal becomes unable to perform the non-3gppaccess, such as if the terminal secedes from a coverage for the non-3gppaccess or if a non-3gpp access module is turned off, the terminaloperates a timer and waits for until the non-3gpp access can be usedagain for a predetermined time (11-12).

If the use of the non-3gpp access is still impossible, such as if theterminal returns to the coverage for the non-3gpp access or the non-3gppaccess module is turned on again, until the timer expires, the terminalmay release the PDU sessions being used through the non-3gpp access ormay trigger to perform deregistration for the non-3gpp access inaccordance with the existing configuration or a user's input (11-13).

For this, the terminal performs a process at operation 11-14, andparticularly in a case where the terminal releases the PDU sessionsbeing used through the non-3gpp access, it transfers a PDU sessionrelease request message 11-15 to an AMF through the 3gpp access withrespect to the corresponding PDU session. The PDU session releasemessage include the corresponding PDU session ID.

The AMF having received the message sends a PDU session release requestto the SMF managing the PDU session corresponding to the PDU session IDto make the SMF and the UPF release the PDU session corresponding to thePDU session ID, and notifies the N3IWF to release a tunnel between theN3IWF and the UPF through the AMF so as to erase the PDU sessions usedthrough the non-3gpp access from the 5G network (11-18).

In contrast, if the terminal performs deregistration for the non-3gppaccess, it transfers a deregistration request message 11-16 for thenon-3gpp access to the AMF through the 3gpp access. The AMF requests thecorresponding SMF to release all the PDU sessions being used through thenon-3gpp access (11-17). Further, the requested SMF performs a PDUsession release (11-18). Further, after performing deregistration forthe non-3gpp access, the SMF sends a deregistration accept (non-3gppaccess) message to the terminal through the 3gpp access (11-19).

FIG. 12 illustrates a process in which a terminal transfers a PDUsession of a non-3gpp access to a 3gpp access through the 3gpp access ifthe terminal accessing a 5G network through the 3gpp access and thenon-3gpp access is unable to use the non-3gpp access according to anembodiment of the disclosure.

A terminal 12-01 that has successfully registered on a 5G networkthrough a 3gpp access and a non-3gpp access uses a PDU session generatedthrough the non-3gpp access (12-11).

In this case, if the terminal becomes unable to perform the non-3gppaccess, such as if the terminal secedes from a coverage for the non-3gppaccess or if a non-3gpp access module is turned off, the terminaloperates a timer and waits for until the non-3gpp access can be usedagain for a predetermined time (12-12).

If the use of the non-3gpp access is still impossible, such as if theterminal returns to the coverage for the non-3gpp access or the non-3gppaccess module is turned on again, until the timer expires, the terminalmay trigger to transfer the PDU sessions being used through the non-3gppaccess to the 3gpp access in accordance with the existing configurationor a user's input (12-13).

For this, the terminal transfers a PDU session establishment requestmessage 12-14 to the AMF through the 3gpp access with respect to thecorresponding PDU session in order to transfer the PDU sessions beingused through the non-3gpp access. The PDU session establishment requestmessage includes the corresponding PDU session ID and an indication forindicating a situation in which the PDU session is transferred to the3gpp access.

The AMF having received the message sends a PDU session establishmentrequest to the SMF managing the PDU session corresponding to the PDUsession ID, and the SMF makes a tunnel for the PDU session through a 5GRAN, that is, 5G base station, through the UPF, and erases the tunnelbetween the existing UPF and the N3IWF. Accordingly, the PDU session istransferred so that the PDU session is serviced through the 3gpp accessrather than the non-3gpp access (12-15), and the UPF through the AMF soas to erase the PDU sessions used through the non-3gpp access from the5G network (11-18).

FIG. 13 illustrates a process of releasing a PDU session of a non-3gppaccess or deregistering a non-3gpp if an AMF recognizes through an N3IWFthat a terminal accessing a 5G network through a 3gpp access and thenon-3gpp access is unable to use the non-3gpp access according to anembodiment of the disclosure.

A terminal 13-01 that has successfully registered on a 5G networkthrough a 3gpp access and a non-3gpp access uses a PDU session generatedthrough the non-3gpp access (13-11).

In this case, if the terminal becomes unable to perform the non-3gppaccess, such as if the terminal secedes from a coverage for the non-3gppaccess or if a non-3gpp access module is turned off, and the N3IWF 13-02notifies the AMF that the non-3gpp access becomes impossible, the AMFoperates a timer and waits for until the non-3gpp access can be usedagain for a predetermined time (13-12).

If the use of the non-3gpp access is still impossible until the timerexpires, the AMF may release the PDU session being used through thenon-3gpp access in accordance with the configuration or policy of anoperator. In this case, the AMF may send a PDU session release requestto the SMF managing the PDU session being used through the non-3gppaccess to make the SMF and UPF release the PDU session corresponding tothe PDU session ID, and may notify the N3IWF through the AMF to releasea tunnel between the N3IWF and the UPF so as to erase the PDU sessionsused through the non-3gpp access from the 5G network.

In contrast, if the AMF performs deregistration for the non-3gpp accessin accordance with the configuration or the policy of the operator, itrequests the corresponding SMF to release all the PDU sessions beingused through the non-3gpp access. The SMF having been requested releasesthe PDU session release, and switches the non-3gpp access to aderegistration state (13-18).

On the other hand, since the terminal has been registered for the 3gppaccess, it sends the registration request message to the AMF through the3gpp access in order to update the registration in accordance withmobility of the terminal or periodically (13-14). In response to this,the AMF sends to the terminal a registration accept message including anindication for notifying that the PDU session for the non-3gpp access isto be released or an indication for notifying that the 5G core networkhas performed deregistration for the non-3gpp access (10-15). Based onthe received indication, the terminal may match synchronization with the5G core network, such as the terminal locally releases the PDU sessionfor the non-3gpp access, or locally performs deregistration for thenon-3gpp access.

FIG. 14 illustrates a process of releasing a PDU session of a non-3gppaccess or deregistering a non-3gpp through a 3gpp access if an AMFrecognizes through an N3IWF that a terminal accessing a 5G networkthrough the 3gpp access and the non-3gpp access is unable to use thenon-3gpp access according to an embodiment of the disclosure.

A terminal 14-01 that has successfully registered on a 5G networkthrough a 3gpp access and a non-3gpp access uses a PDU session generatedthrough the non-3gpp access (14-11).

In this case, if the terminal becomes unable to perform the non-3gppaccess, such as if the terminal secedes from a coverage for the non-3gppaccess or if a non-3gpp access module is turned off, and the N3IWF 14-02notifies the AMF that the non-3gpp access becomes impossible, the AMFoperates a timer and waits for until the non-3gpp access can be usedagain for a predetermined time (14-12).

If the use of the non-3gpp access is still impossible until the timerexpires, the AMF may release the PDU session being used through thenon-3gpp access in accordance with the configuration or policy of anoperator. In this case, the AMF sends a PDU session release request14-14 to the SMF managing the PDU session being used through thenon-3gpp access, and the SMF performs a NW initiated PDU session releaseprocess so as to release the PDU session corresponding to the PDUsession ID, and notifies the N3IWF through the AMF to release a tunnelbetween the N3IWF and UPF, so as to erase the PDU sessions used throughthe non-3gpp access from the 5G network (14-15).

In contrast, if the AMF performs deregistration for the non-3gpp accessin accordance with the configuration or the policy of the operator, itsends the PDU session release request 14-14 to the SMF managing the PDUsession being used through the non-3gpp access, and the SMF performs theNW initiated PDU session release process so as to release the PDUsession corresponding to the PDU session ID, and notifies the N3IWFthrough the AMF to release the tunnel between the N3IWF and the UPF, soas to erase the PDU sessions used through the non-3gpp access from the5G network (14-15). Further, in order to perform deregistration for thenon-3gpp access, the AMF sends a NW triggered deregistration request(non-3gpp access) to the terminal (14-16).

FIG. 15 illustrates a process of switching a PDU session of a non-3gppaccess to a 3gpp access through the 3gpp access if an AMF recognizesthrough an N3IWF that a terminal accessing a 5G network through the 3gppaccess and the non-3gpp access is unable to use the non-3gpp accessaccording to an embodiment of the disclosure.

A terminal 15-01 that has successfully registered on a 5G networkthrough a 3gpp access and a non-3gpp access uses a PDU session generatedthrough the non-3gpp access (15-11).

In this case, if the terminal becomes unable to perform the non-3gppaccess, such as if the terminal secedes from a coverage for the non-3gppaccess or if a non-3gpp access module is turned off, and the N3IWF 15-02notifies the AMF that the non-3gpp access becomes impossible, the AMFoperates a timer and waits for until the non-3gpp access can be usedagain for a predetermined time (15-12).

If the use of the non-3gpp access is still impossible until the timerexpires, the AMF may release the PDU session being used through thenon-3gpp access in accordance with the configuration or policy of anoperator. In this case, the AMF may send a PDU session release request15-13 to the SMF managing the PDU session being used through thenon-3gpp access, and may send a PDU session modification request to theterminal so as to switch the PDU session corresponding to the PDUsession ID to the 3gpp access. The request message includes the PDUsession ID and an indication indicating switchover to the 3gpp access(15-14).

The terminal having received the request transfers a PDU sessionestablishment request message 15-15 to the AMF through the 3gpp accesswith respect to the corresponding PDU session in order to transfer thePDU sessions being used through the non-3gpp access to the 3gpp access.The PDU session establishment request message includes the correspondingPDU session ID and an indication for indicating a situation in which thePDU session is transferred to the 3gpp access.

The AMF having received the message sends the PDU session establishmentrequest message to the SMF managing the PDU session corresponding to thePDU session ID, and the SMF makes a tunnel for the PDU session through a5G RAN, that is, 5G base station, through the UPF, and erases the tunnelbetween the existing UPF and the N3IWF. Accordingly, the PDU session istransferred so that the PDU session is serviced through the 3gpp accessrather than the non-3gpp access (15-16).

FIG. 16 illustrates a process of performing registration management andconnection management if a terminal accessing a 5G network through a3gpp access and a non-3gpp access recognizes that it is unable to usethe non-3gpp access according to an embodiment of the disclosure.

If a terminal that has successfully registered on a 5G network through a3gpp access and a non-3gpp access uses a PDU session generated throughthe non-3gpp access becomes unable to perform the non-3gpp access, suchas if the terminal secedes from a coverage for the non-3gpp access or ifa non-3gpp access module is turned off, it operates a timer and waitsfor until the non-3gpp access can be used again for a predetermined time(16-01).

If the terminal is set to switch a PDU session for the non-3gpp accessto the 3gpp access or a user selects to do so in a state where the useof the non-3gpp access is impossible until the timer expires (16-02),the terminal starts a procedure of transferring the PDU session for thenon-3gpp access to the 3gpp access 16-03), and for this, the terminalsends a PDU session establishment request message to the SMF through anAMF to switch the PDU session to be used through the 3gpp access. Forthis, the PDU session establishment request message includes a PDUsession ID of the PDU session to be transferred and an indication fornotifying the switchover to the 3gpp access.

On the other hand, if the terminal is set to release the PDU session forthe non-3gpp access or the user selects to do so in a state where theuse of the non-3gpp access is impossible until the timer expires(16-05), the terminal locally releases the PDU session for the non-3gppaccess, or performs local deregistration for the non-3gpp accessaccording to the setting (16-06). Thereafter, when the terminal performsregistration update through the 3gpp access, the registration requestmessage may include an indication for notifying that the PDU session forthe non-3gpp access is to be released or an indication for notifyingthat the local deregistration has been performed for the non-3gpp access(16-07).

On the other hand, the terminal may send a PDU session release requestto release the PDU session for the non-3gpp access, or may send a UErequested deregistration request (non-3gpp access) message to the 5Gcore network for the deregistration for the non-3gpp access inaccordance with the setting (16-08).

FIG. 17 illustrates a process of performing registration management andconnection management if an AMF recognizes through an N3IWF that aterminal accessing a 5G network through a 3gpp access and a non-3gppaccess is unable to use the non-3gpp access according to an embodimentof the disclosure.

If a terminal that has successfully registered on a 5G network through a3gpp access and a non-3gpp access becomes unable to perform the non-3gppaccess, such as if the terminal secedes from a coverage for the non-3gppaccess or if a non-3gpp access module is turned off, and an N3IWFnotifies an AMF that the non-3gpp access becomes impossible, the AMFoperates a timer and waits for until the non-3gpp access can be usedagain for a predetermined time (17-01).

If it is set to switch a PDU session for the non-3gpp access to the 3gppaccess or a service provider's policy selects to do so in a state wherethe use of the non-3gpp access is impossible until the timer expires(17-02), the AMF requests the SMF to perform a procedure of transferringthe PDU session for the non-3gpp access to the 3gpp access (17-03). Forthis, the SMF sends a PDU session modification request to the terminalto switch the PDU session to the 3gpp access (17-04).

The terminal sends a PDU session establishment request message to theSMF through the AMF to switch the PDU session through the 3gpp access.For this, the PDU session establishment request message includes a PDUsession ID of the PDU session to be transferred and an indication fornotifying the switchover to the 3gpp access.

On the other hand, if it is set to release the PDU session for thenon-3gpp access or the service provider's policy selects to do so in the5G core network in a state where the use of the non-3gpp access isimpossible until the timer expires (17-05), the AMF releases the PDUsession for the non-3gpp access through the SMF, or performs localderegistration for the non-3gpp access according to the setting (17-06).Thereafter, when the terminal performs registration update through the3gpp access, the registration accept message may include an indicationfor notifying that the PDU session for the non-3gpp access is to bereleased or an indication for notifying that the local deregistrationhas been performed for the non-3gpp access (17-07).

On the other hand, the AMF may send a PDU session release request to theterminal through the 3gpp access in order to release the PDU session forthe non-3gpp access through the SMF, or may send a NW-requestedderegistration request (non-3gpp access) message to the terminal throughthe 3gpp access for the deregistration for the non-3gpp access inaccordance with the setting (17-08).

FIG. 18 is a diagram illustrating a structure of a network entityaccording to embodiments of the disclosure. The network entity may referto each configuration of the network shown in FIG. 1 to FIG. 17 . Forexample, referring to FIG. 1 , the network entity may be a base station(RAN), Common AMF, SMF, N3IWF, and the like. For example, referring toFIG. 5 , the network entity may be RAN, AMF, NRF, SMF, UPF, and thelike. For example, referring to FIG. 9 , the network entity may be RAN,AMF, NRF, SMF, UPF, N3IWF, and the like.

Referring to FIG. 18 , the network entity may include atransmission/reception unit (or transceiver) 1810, a control unit (or acontroller or at least one processor) 1820, and a storage unit 1830(e.g., a memory). In the disclosure, the control unit may be defined asa circuit or an application specific integrated circuit or at least oneprocessor.

The transmission/reception unit 1810 may transmit and receive signals toor from a terminal or another network entity. The control unit 1820 maycontrol the overall operation of the network entity according to theembodiment of the disclosure. For example, the control unit 1820 maycontrol the signal flow between each block to perform the operationaccording to the flowcharts described above.

The storage unit 1830 may store at least one of information transmittedand received through the transmission/reception unit 1810 andinformation generated through the control unit 1820.

FIG. 19 is a diagram illustrating a structure of a terminal according toan embodiment of the disclosure.

Referring to FIG. 19 , the terminal may include a transmission/receptionunit (or transceiver) 1910, a control unit (or a controller or at leastone processor) 1920, and a storage unit 1930 (e.g., a memory). In thedisclosure, the control unit may be defined as a circuit or anapplication specific integrated circuit or at least one processor.

The transmitting/receiving unit 1910 may transmit and receive signalswith other network entities. The transmitting/receiving unit 1910 mayreceive system information from, for example, a base station and mayreceive a synchronization signal or a reference signal.

The control unit 1920 can control the overall operation of the terminalaccording to the embodiment of the disclosure. For example, the controlunit 1920 may control the signal flow between each block to perform theoperation according to the flowcharts described above.

The storage unit 1930 may store at least one of information transmittedand received through the transmitting/receiving unit 1910 andinformation generated through the control unit 1920.

In the embodiments of the disclosure as described above, constituentelements included in the disclosure are expressed in a singular form orin a plural form. However, such a singular or plural expression isselected to suit a situation presented for convenience in explanation,and thus the disclosure is not limited to such singular or pluralconstituent elements. Even plural constituent elements may be expressedin a singular form, and even a single constituent element may beexpressed in a plural form.

Although detailed embodiments of the disclosure have been described inthe specification and drawings, it will be apparent that variousmodifications are possible within the scope of the disclosure.Accordingly, the scope of the disclosure should not be limited to theembodiments as described above, but should be defined by the appendedclaims below and those equivalent to the scope of the claims.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method of performing access deregistration byan access and mobility management function (AMF) serving a 3rdgeneration partnership project (3GPP) access and a non-3GPP access, themethod comprising: assigning, to a terminal, a temporary identifier (ID)during a registration procedure over the 3GPP access in a public landmobile network (PLMN), the assigned temporary ID is re-used in aregistration procedure over the non-3GPP access for the terminal in thePLMN; determining to initiate a deregistration procedure over the 3GPPaccess to deregister the non-3GPP access for the terminal, after theterminal is registered over the 3GPP access and the non-3GPP access; andtransmitting, to a session management function (SMF) based on thedetermination, a request for releasing a protocol data unit (PDU)session including a non-3GPP access PDU session ID, wherein all PDUsessions associated with the non-3GPP access are released based on therequest.
 2. The method of claim 1, further comprising: receiving, fromthe terminal, a deregistration request message to deregister thenon-3GPP access for the terminal over the 3GPP access, in case that thederegistration procedure is initiated by the terminal; and transmitting,to the terminal, a deregistration accept message corresponding to thederegistration request message over the 3GPP access.
 3. The method ofclaim 1, wherein the deregistration procedure is initiated by theterminal in case that the terminal is out of a coverage for the non-3GPPaccess.
 4. The method of claim 1, wherein the deregistration procedureis initiated based on no connection of the non-3GPP access for theterminal.
 5. The method of claim 1, further comprising: performingseparate registration management for the 3GPP access and the non-3GPPaccess, wherein the determining to initiate a deregistration procedurefurther comprises: determining to operate a timer associated with thenon-3GPP access, in case that the terminal is unable to use the non-3GPPaccess, and identifying that the timer associated with the non-3GPPaccess is expired.
 6. An access and mobility management function (AMF)serving a 3rd generation partnership project (3GPP) access and anon-3GPP access for performing access deregistration, the AMFcomprising: a transceiver; and a controller coupled with the transceiverand configured to control to: assign, to a terminal, a temporaryidentifier (ID) during a registration procedure over the 3GPP access ina public land mobile network (PLMN), the assigned temporary ID isre-used in a registration procedure over the non-3GPP access for theterminal in the PLMN, determine to initiate a deregistration procedureover the 3GPP access to deregister the non-3GPP access for the terminal,after the terminal is registered over the 3GPP access and the non-3GPPaccess, and transmit, to a session management function (SMF) based onthe determination via the transceiver, a request for releasing aprotocol data unit (PDU) session including a non-3GPP access PDU sessionID, wherein all PDU sessions associated with the non-3GPP access arereleased based on the request.
 7. The AMF of claim 6, wherein thecontroller is further configured to: receive, from the terminal via thetransceiver, a deregistration request message to deregister the non-3GPPaccess for the terminal over the 3GPP access, in case that thederegistration procedure is initiated by the terminal, and transmit, tothe terminal via the transceiver, a deregistration accept messagecorresponding to the deregistration request message over the 3GPPaccess.
 8. The AMF of claim 6, wherein the deregistration procedure isinitiated by the terminal in case that the terminal is out of a coveragefor the non-3GPP access.
 9. The AMF of claim 6, wherein thederegistration procedure is initiated based on no connection of thenon-3GPP access for the terminal.
 10. The AMF of claim 6, wherein thecontroller is further configured to: perform separate registrationmanagement for the 3GPP access and the non-3GPP access, determine tooperate a timer associated with the non-3GPP access, in case that theterminal is unable to use the non-3GPP access, and identify that thetimer associated with the non-3GPP access is expired.
 11. A method ofperforming access deregistration by a terminal, the method comprising:receiving, from an access and mobility management function (AMF), anassigned temporary identifier (ID) during a registration procedure overa 3rd generation partnership project (3GPP) access in a public landmobile network (PLMN), the assigned temporary ID is re-used in aregistration procedure over a non-3GPP access for the terminal in thePLMN, wherein a deregistration procedure over the 3GPP access toderegister the non-3GPP access for the terminal is initiated by the AMFafter the terminal is registered over the 3GPP access and the non-3GPPaccess, wherein a request for releasing a protocol data unit (PDU)session including a non-3GPP access PDU session ID is transmitted, fromthe AMF to a session management function (SMF), and wherein all PDUsessions associated with the non-3GPP access are released based on therequest.
 12. The method of claim 11, further comprising: transmitting,to the AMF, a deregistration request message to deregister the non-3GPPaccess for the terminal over the 3GPP access, in case that thederegistration procedure is initiated by the terminal; and receiving,from the AMF, a deregistration accept message corresponding to thederegistration request message over the 3GPP access.
 13. The method ofclaim 11, wherein the deregistration procedure is initiated by theterminal in case that the terminal is out of a coverage for the non-3GPPaccess.
 14. The method of claim 11, wherein the deregistration procedureis initiated based on no connection of the non-3GPP access for theterminal.
 15. The method of claim 11, wherein separate registrationmanagement for the 3GPP access and the non-3GPP access is performed,wherein a timer associated with the non-3GPP access is operated, in casethat the terminal is unable to use the non-3GPP access, and wherein thetimer associated with the non-3GPP access is expired is identified bythe AMF.
 16. A terminal for performing access deregistration, theterminal comprising: a transceiver; and a controller coupled with thetransceiver and configured to control to: receive, from an access andmobility management function (AMF) via the transceiver, an assignedtemporary identifier (ID) during a registration procedure over a 3rdgeneration partnership project (3GPP) access in a public land mobilenetwork (PLMN), the assigned temporary ID is re-used in a registrationprocedure over a non-3GPP access for the terminal in the PLMN, wherein aderegistration procedure over the 3GPP access to deregister the non-3GPPaccess for the terminal is initiated by the AMF, after the terminal isregistered over the 3GPP access and the non-3GPP access, wherein arequest for releasing a protocol data unit (PDU) session including anon-3GPP access PDU session ID is transmitted, from the AMF to a sessionmanagement function (SMF), and wherein all PDU sessions associated withthe non-3GPP access are released based on the request.
 17. The terminalof claim 16, wherein the controller is further configured to: transmit,to the AMF via the transceiver, a deregistration request message toderegister the non-3GPP access for the terminal over the 3GPP access, incase that the deregistration procedure is initiated by the terminal, andreceive, from the AMF via the transceiver, a deregistration acceptmessage corresponding to the deregistration request message over the3GPP access.
 18. The terminal of claim 16, wherein the deregistrationprocedure is initiated by the terminal in case that the terminal is outof a coverage for the non-3GPP access.
 19. The terminal of claim 16,wherein the deregistration procedure is initiated based on no connectionof the non-3GPP access for the terminal.
 20. The terminal of claim 16,wherein separate registration management for the 3GPP access and thenon-3GPP access is performed, wherein a timer associated with thenon-3GPP access is operated, in case that the terminal is unable to usethe non-3GPP access, and wherein, that the timer associated with thenon-3GPP access is expired is identified by the AMF.